In a color image sensor apparatus, generally a standard color television signal of NTSC system or the like is formed from image sensor outputs, which are obtained by separating the light of a scene into a plurality of component color images through a color separating system and sensing the individual component color images with solid-state image sensors such as CCDs or an image pick-up tube. In a color image sensor apparatus using a plurality of image sensors, it is necessary to reliably maintain the state of overlap of individual component color images obtained from respective image sensors or the state in which so-called registration adjustment is accurately made.
In a conventional color video camera of so-called three-tube type, a three-color separating prism of a color separating system and three image pick-up tubes are mechanically mounted in a housing which is formed by die casting or the like, and the registration adjustment of each image pick-up tube is done by effecting mechanical positional adjustment according to an output signal obtained by picking up a test chart or the like and fine adjusting the image pick-up screen position by utilizing the deflection system of the image pick-up tubes.
In a solid-state color image sensor apparatus using solid-state image sensors such as CCDs as image sensors, unlike the color video camera of the three tube type noted above, electrical image pick-up screen positional adjustment as in the image pick-up tube can not be done. Therefore, a holder made of iron or like material is bonded to each solid-state image sensor for sensing each component color image, while the holder is bonded to each light exit section of the color separating prism of the color separating system. For each image sensor, registration adjustment in six different directions, i.e., (1) adjustment of the center in the horizontal direction (i.e., .+-.X directions as shown by arrows), (2) adjustment of the center in the vertical direction (i.e., .+-.Y directions as shown by arrows), (3) adjustment of back focus (i.e., .+-.Z directions as shown by arrows), (4) adjustment of tilt and shift in the horizontal direction (i.e., .+-.RX directions as shown by arrows), (5) adjustment of the tilt and shift in the vertical direction (i.e., .+-.RY directions as shown by arrows) and (6) adjustment of rotation (i.e., .+-.RZ directions as shown by arrows), is done as shown in FIG. 13, and then both of holders are thermally bonded together by means of soldering. In this way, each solid-state image sensor is mounted by securement on each light exit surface of the color separating prism.
In the meantime, the solid-state image sensor such as CCD is incapable of electric image pick-up screen positional adjustment as in the image pick-up tube. Therefore, in the color image sensor apparatus using a plurality of solid-state image sensors, it is necessary to mechanically maintain a very high precision of the registration of each image sensor. Particularly, in a solid-state color image sensor apparatus adopting a so-called space picture element shift system for increasing the resolution, it is necessary to ensure registration of the order of 1 .mu.m in the afore-mentioned six directions, i.e., .+-.X, .+-.Y, .+-.Z, .+-.RX, .+-.RY and .+-.RZ directions. Therefore, the conventional registration adjustment has requires a great deal of skill and time.
An object of the present invention, accordingly, is to permit registration adjustment in the afore-mentioned six directions in a simple operation and with a high precision.